Diesel engine



May. 14, 1935. w. LEHMANN DIESEL ENGINE Filed Feb. 20, 1934 FIG; 6

. W lu/mann- Patented May 14, 1935 UNITED STATES `DIESEL ENGINE WillyLehmann, Eichwalde, near Berlin, Germany, assigner to Heinrich KamperMotorenfabrik Aktiengesellschaft, Berlin-Marienfelde,

Germany Application February 20, 1934, Serial No. '712,185 In GermanyMarch 12, 1932 4 claims. (ci. 12s-182) The present invention relates toan arrang ment and process for starting Diesel engines, moreparticularly lDiesel engines used for working tugs, fishing boats or thelike, that is to say g engines in which strong construction and greatsimplicity are of importance.

The present arrangement and the present starting process make itpossible to start the Diesel engines in an easy and convenient manner byhand from cold even in cold weather if desired, or by means of a smallstarting motor of any desired kind.

It has been found that it is impossible to change over directly theworking process from the starting during which the engine works as anordinary explosion engine, to the working as a Diesel engine.

With the hitherto known method of changing over it'is impossible toavoid immediately after the changing over, the presence of petrol in thecylinder chamber, and this results in heavy petrol explosions in thecylinder, injurious to the working, as immediately after the changingover, a high compression is produced and the engine acts as a Dieselengine.

The object of the present invention is to eliminate these drawbacks.

'Ihe complete or nearly complete elimination o! petrol from thecylinderl at the moment of the n first high compression is obtained bythe followingmeans:

The connection valve between the main compression chamber and theadditional compression chamber, which is open during the rst startingperiod, in which the engine works as an ordinary explosion engine, isclosed, the admission valve proper of the engine is closed too and isnot working.

The two valves mentioned remain thereupon closed for a certain period oftime. The result of this is that during the suction period there isproduced in the cylinder a more or less high vacuum whereupon acorrespondingly smaller compression takes place `during the compressionperiod. At the third half revolution '(in normal state this would be thecombustion period), a certain vacuum is produced again at the end of thestroke whereupon, after the opening of the exhaust valve which alwaystakes place in the normal manner, air ilows back from the silencer andis immediately expelled again. In this way a washing or scavenging ofthe cylinder takes place in as far as the processes described extendover one or more revolutions. The petrol disappears therefore from thecylinder.

Only now the control of the admission valvev properis released, and theengine Works as a\ Diesel engine.

In order to obtain the action described, itis -therefore necessary tomake an arrangement which would ensure that a certain time will passafter the closing of the valve between the compression chamber properand .the additional A compression chamber, before it is possible to openthe admission valve and to allow its control to become effective.

The whole process together with the corresponding arrangements isparticularly suitable also for medium pressure engines (in combinationwith a heat accumulator near the fuel nozzle) as according to thepresent process the engine is pre-heated so that ignition of the Dieseldriving medium is produced at relatively lower degrees of compression.

In the accompanying drawing:

Fig. 1 is a vertical section through the cyl-'- inder.

Fig. 2 a plan of Figure 1. Fig. 3 a section on line A-A of Figure 2.Cylinder and admission valve during the Diesel working.

Fig. 4'the same as Figure 3, but in the starting position.

Fig. 5 is a part of Fig. 1. The change-over valve is in the startingposition.

Fig. 6 is a section on line B-B of Fig. 2. Cylinder and exhaust valve.

Fig. 7 the change-over crank handle. In the drawing, a is `the chamberor space above the piston, b` the compression chamber proper, c the fuelnozzle, d the additional com`v pression chamber, e the valve drawing inthe mixture, through which a mixture of petrol and air can get to d, f asparking plug which is preferably actuated by a magneto apparatus, thekamature of which is moved jerkily in a. manner well known in itself whenthe. number of revolutions is low, in order to provide suicient ignitioncurrent.

a is the change-over valve which shuts ofi' the compression chamber aand b from the auxiliary compression chamber d. 'I'he valve g is appliedto its seat by a spring, h is a. two-armed lever, i a shaft which isturned by hand only during the changing over from the starting to theDiesel period and is prevented from rotating both during the startingperiod and during the Diesel working period. In each position of thisshaft it forms the axis of rotation for the lever of the exhaust valve.With the use of an eccentric however it forms also the axis of rotationof the lever of the admission valve.

k is the lever of the exhaust valve and l the exhaust valve. The controlof the exhaust valve is unmodied during the starting, during the Dieselworking as well as during the time provided mording to the inventionbetween the two workm is'acam on'the shaft i which raises the valve g`on a corresponding turning o f i. n is an eccentric rigidly secured tothe shaft i, which forms the pivot point of theadmission lever. o is theadmission valve lever. p a crank handle operated by handwhich in thedrawing is moved 1 in the anti-clockwise direction (see also Figure 7).'I'he crank handle p is rigidly securedv to the shaft i. j q is (forinstance) a handle with a correspond-- ing pin which is pressed by aspring against a ring. s the said ring which is iixed relatively to thecylinder head, r a recess in the ring s Awhich extends over a givenangle, (see the following explanation), t the cam for the exhaust valve,u a heat accumulator in the chamber b which isrequired if the engine isrun as a medium pressure engine. j

'I'he working of the arrangement is as fol- During the starting thecrank p is in the position I. The cam m is then in the positionindicated in Figure 5, it raises the valve a and re- `leasestheconnection between d, a and b.

111e engine works then as a four-stroke petrol engine, the admissionvalve proper (compare Fig- In this starting position, the pin of thebutton q engages with the groove r.

'Ihe change over to the Diesel process takes place as follows:

`After the crank has reached the position II. the lever h (compareFigure 5) springs of! from the cam m. Y

In the position III, the valve g is, completely closed (Figure 1,) butalso the admission valve of the engine still remains completely closed(Figure 4) in view of a corresponding dimensioning of the eccentric n.Between the positions III and IV in Figure 7, the control of theadmissiu on valve gradually begins to become opera ve.v

Without the provision of the recess r or of a corresponding otherarrangement, the engine could be changed over almost instantaneouslyfrom the starting position to the working'position. This would result inexplosions of the petrol still contained in the cylinder chamber.

But the pin connected to the handle q (Figure 2)is in the groove r`(Figure 7) already before the position AI is reached and if desiredevenearlier. The groove ends at an angle at which the eccentric n is stillin such a. position that the lever o does not yet open the admissionvalve at any point. The crank p cannot be at first turned beyond thisangle.

In order to make possible a further turning of the crank p, the operatorwho wants to start the engine working, must for instance release p, thenpull out the button q so that it shall no longer engage with' the groover, and only then 'I'his results in an intended loss of time.

In as far as the above mentioned time-wast-i ing manipulations last forinstance only one second, and in as faras the engine makes in startingat the moment of changing over say 420 revolutions per minute, all thepetrol traces will be Washed out of the cylinder during the time lost byseven revolutions of the engine.

If this loss of time is considered too large, the handle of the crank pand the button q could be made to coincide.. V 1

The whole starting arrangement offers particular advantages incombination with. medium pressure engine. As is well known, the latterare characterized in that their compression is always suflicientlystrong to enable them to work in warm state (preferably in combinationwith the heat accumulator u) (Figure l) on the Diesel principle, whilstthe compression is'not so great as to enable the engine to start in are-A liable manner from cold with cold atmospheric air. The startingdevice such as it is here described pre-heats the engine in a mannerwell known in itself, and venables it to work on the Diesel principlewith a weaker compression:

At the same time however' the general arrangement hereinbefore describedwhich eliminates the petrol from the cylinder, becomes of particularimportance, for the advantage of being able to build the engine lightersince it has to withstand only medium pressures would disappear if ithad to be built strong enough to be able to withstand the heavy initialpetrol explosions. f

I claim:

l. In a ADiesel engine, the combination of ay main compression chamber,an admission valve, an exhaust valve and actuating mechanism for saidexhaust valve with an additional compression chamber in communicationwith the main compression chamber and having a supply inlet foradmitting a starting fuel, a change-over valve for closing thecommunication, between the main and additional compression chambers,operating means for moving the change-over valve into and out of theclosing position and actuating mechanism for the admission valveincluding an actuating member adjustable from an operative position toan inoperative position and adjusting means for said actuating memberoperatively connected to the operating means for the change-over valvefor moving the said actuating member into the inoperative position o nthe change-over valve being moved into the open position and into theoperative position after the change-over valve has been moved into theclosing position, so as to prevent the admission valve opening while themain and additional compression chambers are in communication with oneanother.

2,. In a Diesel engine, lthe combination 'of a main compression chamber,an admission valve, an exhaust valve and actuating mechanism for saidexhaust valve with an additional compression chamber in. communicationwith the main compression chamber and having a supply inlet.

for admitting a. starting fuel, a change-over valve for closing thecommunication between the main and additional. compression chambers,operating means for moving the change-over valve into and out of theclosing position and actuating mechanism for the admission valve,including an actuatingmember adjustable from an operative to an angularposition in which the valve lever position to an inoperative positionand adjusting means for said actuating member operatively connected tothe operating means for the changeover valve formoving the saidactuating member into the inoperative position on the change-over valvebeing moved into the open position, said adjusting means being arrangedto move the actuating member into the operative position after thechange-over valve has been moved into the closing position, and checkingmeans for retarding the movement of the adjusting means beyond theclosing position of the change-over valve so as to enable the engine toperform a number of idle strokes with the admission valveclosed.

3. In a Diesel engine, the Acombination of a main compression chamber,anadmission valve, an exhaust valve and actuating mechanism for saidexhaust valve with an additional compression chamber in communicationwith the main compression chamber and having a Supply inlet toradmitting a starting fuel, a change-over valve for closing thecommunication between the main and additional compressionv chambers,operating means for moving the change-over valve into and out of theclosing position and actuating mechanism for the admission valve,including a valve lever, an eccentric pivot for said valve leverturnable from an angular position in which the valve lever is inoperative relationship with theA valve is out of operative relationshipwith the valve, a control shaft Vxed to said eccentric pivot andoperatively connected to the .operating means for the change-over'valveso as to bring the valve lever out of operative relationship with thevalve on the change-over valve being moved into the open position andinto operative relationship with the valve after the change-over valvehas been moved into the closing position.

4. In a Diesel engine, the combination as set forth in claim 2, in whichthe operating means for the change-over valve comprises an operatinghandle and the checking means comprise a positive stop member associatedwith said operating handle and a iixed stop arranged forcooperation'with the, movable stop member to arrest the movement of theoperating handle when the change-over valve is in the closing positicm,said movable stop member being movable from a posit-ion in which it canengage the xed lstop into a position in which it is incapable of suchengagement, whereby the further movement o! the operating handle beyondthat corresponding to the closing position of the change-over valve isdelayed until the movable stop member is moved into the second-mentionedposition.

WILLY LEHIVIANN.

